Power supply

The power supply (electrical, pneumatic or hydraulic, as necessary) should be compatible with the I C system. The power supply for I C systems important to safety should have classification, qualification, isolation, testability, maintainability and indication of removal from service, consistent with the reliability requirements of the I C systems they serve. 

I C systems important to safety that are required to be available for use at all times in operational states or design basis accident conditions should be connected to a non-interruptible power supply. The performance requirements of non-intermptible power supplies should satisfy the requirements of the system that they power. 

I C systems important to safety may be connected by the plant operators or by automatic switching action to a stand-by power supply instead of the normal supply when operating circumstances warrant, provided that the functions of the I C systems can tolerate the associated interruption in supply. The transfer system should in most cases be considered an extension of the power supply system(s). 

Digital computer systems are used in I C systems important to safety to perform functions of protection, data acquisition, computation, control monitoring and display. If properly designed, they can offer the advantages of improved reliability, accuracy and functionality in comparison with analog systems. The computer system 

Computer systems may be used to advantage in detecting and monitoring faults internal and external to plant systems and equipment important to safety. 

Before starting to discuss troubleshooting for specific power supplies, some general comments, and some hints for troubleshooting, are given. The discussion on some specific power supplies is presented in Sections 5.3 through 5.7. 

The linear regulated supplies with power transformer, rectifiers, capacitor filtering, pass transistor, current sense resistor for current limitation either for constant current or with foldback characteristics and the error amplifier including the voltage reference source. 

The switched mode power supply with direct ac line rectifying, filtering, fast switching power transistors, ferrlt-core transformer for power transfer, fast 

Occasionally, we might find that the designer made a wrong selection of the diodes the assumed specifications do not correspond with the ratings. Typical examples are with the frequency of the mains (50 60Hz) or voltage (117 220V). 

In older equipment, capacitors may become defective due to heat they are used at the limits of their voltage specifications this is especially true for tantallum drop-form capacitors. Pass or power transistors are mainly destroyed by overvoltage, excessive 

Commercially available combustible gas detection systems generally use 24 VDC as the power supply for field devices. 24 VDC is inherently safer and corresponds the voltages increasing used by most instrument systems in process areas. A main supply voltage converter can be used to step down or convert from AC to DC power supplies. 

A full-wave rectifier is commonly used to convert AC to DC. The current from such a rectifier has a 120 Hz ripple which is of no consequence. The rates of build-up and collapse of concentration boundary layers are so slow compared to the ripple frequency that stack performance is unaffected by the ripple. 

Connections between the power supply and the electrodes are usually made outside the stack so that they can be kept clean and dry. It is advisable that the conductor between this connection and the electrode be of the same material as the electrode and that the connection with the electrode be welded. Otherwise, severe corrosion problems can result. 

The typical voltage drop across a cell pair is in the range of 1 to 2 volts. Ecp does not change greatly as feed concentrations change, because I is proportional to concentration, and Rcp varies inversely with concentration. 

Assuming constant current efficiency, the current is proportional to the amount of salt removed by the passage of current, i.e., I C. Since power consumption is the product of current and voltage, one reaches the not-too-surpris- 

The phenomenon of concentration polarization is important in electrodialysis, because it ultimately limits the rate at which ion transport can occur. Concentration polarization will be discussed first in a descriptive manner. Then, a simplified mathematical model will be used to show the quantitative aspects of concentrations polarization and explain the important concept of limiting current density . 

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For the practical implementation of the above mentioned facts, the portable electronic digital coercive force meter with self-contained power supply, attached converter and closed type magnetic core. Instrument error is 5 %. ... 

Temperatures operating range-Power supply -Overall dimensions -Mass -... 

For testing under field conditions a new mobile version of introscope has been developed, mounted on a lorry with high cross-country capability and self-contained power supply. 

The maximum desilvering speed is related to the maximum current the power supply will deliver. When the efficiency is high, a current of lA will recover 4g of metallic silver per hour. The daily load determines the maximum current required. A 3A unit will typically be used for up to 15 m of film per day. 

The EU contains capacitor battery (CB), current source (CS), accumulator (Ac), controlled by CS, impulse former (IF),power supply (PS), two comparators (Cpl,Cp2),... 

Fig. 1 shows the block diagram of the vibrometer, in which the most sensible to small phase variations interferometric scheme is employed. It consists of the microwave and the display units. The display unit consists of the power supply 1, controller 2 of the phase modulator 3, microprocessor unit 9 and low-frequency amplifier 10. The microwave unit contains the electromechanical phase modulator 3, a solid-state microwave oscillator 4, an attenuator 5, a bidirectional coupler 6, a horn antenna 7 and a microwave detector 11. The horn antenna is used for transmitting the microwave and receiving the reflected signal, which is mixed with the reference signal in the bidirectional coupler. In the reference channel the electromechanical phase modulator is used to provide automatic calibration of the instrument. To adjust the antenna beam to the object under test, the microwave unit is placed on the platform which can be shifted in vertical and horizontal planes. 

The ethemet connection is combined with the power supply to the PSP-4 and the connected scanner into a single standard cable, that can be used for distances up to 100 m. By using special cables, the distance between the PSP-4 and the eontrol unit can be extended to practieally any distance. 

The HILL-SCAN 30XX boards can be used in different PCs. Desktop- and tower-PCs as well suited for laboratory uses. For in-field inspections rugged notebooks and portable PCs are advantageous. A typical portable system is shown in Fig. 2 (USPC 3010), used in MUSE (Mobile Ultrasonic Equipment). This portable PC not only contains the boards for ultrasonic testing but also a controller with power supply for stepper motors, so that a manipulator can be connected directly. The MUSE system is enlarged with a water circulation system which enables a local immersion technique" for in-field inspections. A typical result is shown in Fig. 3, which presents a D-scan of a CFRP- component in RTM-techniques. The defect area caused by an impact is clearly indicated. The manipulator is described in [3]. 

The great advantage of installing an ultrasonic system in a PC is that both the hardware (processor, grafics, power supply,. .) aud the software (evaluation and documentation) are directly available for the inspections. 

In addition to the controlling computer the system contains only a small control unit - PSP-4 (weight approx. 5 kg.) which among other system components includes a motor control system integrated closely with the PS-4 ultrasonic system. For communication between the PSP-4 control unit and the robot as well as robot power supply is used a single cable less than 10 mm. in diameter. 

The electronic block, which includes block of the analysis and registration and control system engines, and block of the source-receiver of acoustic oscillations are universal for any installations of this type. As the source-receiver of acoustic oscillations the ultrasonic flow detector is usually use. It s, as a rule, the serial devices for example y/f2-12. The electronic block contains the microprocessor device or PC, device of the power supply and management of engines... 

The Driving Module houses power supply, circuits for determination of travel distance (odometer wheels) and circumferential orientation, and a computer and a storage facility for all data recorded. The Driving Module has cups extending to the pipe wall, thus providing the movement of the tool after its launching into the continuous oil flow. 

When a battery (or a generator or other power supply) outside the system drives current, i.e. a flow of electric charge, tlirough a wire that passes tlirough the system, work is done on the system ... 

EIOs), backward wave oscillators (BWOs) or magnetrons are available. Their spectral characteristics may be favourable however, they typically require highly stabilized high-voltage power supplies. Still higher frequencies may be obtained using far-infrared gas lasers pumped for example by a CO- laser [49]. 

The heat capacity of a gas at constant pressure is nonually detenuined in a flow calorimeter. The temperature rise is detenuined for a known power supplied to a gas flowing at a known rate. For gases at pressures greater than about 5 MPa Magee et al [13] have recently described a twin-bomb adiabatic calorimeter to measure Cy. 

The basic instrumentation for capillary electrophoresis is shown in Figure 12.41 and includes a power supply for applying the electric field, anode and cathode compartments containing reservoirs of the buffer solution, a sample vial containing the sample, the capillary tube, and a detector. Each part of the instrument receives further consideration in this section. 

Terminal block Vor single point power supply with electric heat) DCE units... 

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